Given a `m x n`

matrix `grid`

which is sorted in non-increasing order both row-wise and column-wise, return *the number of negative numbers in*

`grid`

.

**Example 1:**

Input:grid = [[4,3,2,-1],[3,2,1,-1],[1,1,-1,-2],[-1,-1,-2,-3]]Output:8Explanation:There are 8 negatives number in the matrix.

**Example 2:**

Input:grid = [[3,2],[1,0]]Output:0

**Example 3:**

Input:grid = [[1,-1],[-1,-1]]Output:3

**Example 4:**

Input:grid = [[-1]]Output:1

**Constraints:**

`m == grid.length`

`n == grid[i].length`

`1 <= m, n <= 100`

`-100 <= grid[i][j] <= 100`

`O(n + m)`

solution?
class Solution {
public int countNegatives(int[][] grid) {
}
}